Does an evening coffee, nightcap or a cigarette keep you up? Research has found which of these do and do not affect the quality of your sleep

Not getting enough good quality sleep is linked to numerous adverse health outcomes including heart disease, high blood pressure, diabetes, and certain cancers.

Evening use of alcohol, caffeine and nicotine is believed to sabotage sleep. Yet, studies examining their effects on sleep are limited by small sample sizes.

So, using wrist-watch-like sensors (actigraphy) daily sleep diaries, researchers studied night-to-night associations of evening use of alcohol, caffeine and nicotine on sleep duration, sleep efficiency and wake after sleep onset in 785 people over 5 164 days.

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Good news for coffee drinkers

Results of the study may be good news for coffee lovers as researchers found no link between consumption of caffeine within four hours of bedtime with any of the sleep parameters.

However, the researchers warn that caffeine dosing, and individual variations in caffeine sensitivity and tolerance, were not able to be measured and can play an important role in the association between caffeine use and sleep.

Drinking alcohol and smoking before bed

For smokers and those who enjoy an alcoholic beverage with dinner, the study shows that the use of nicotine and/or alcohol within four hours of bedtime demonstrated worse sleep continuity than a night without these substances.

This was noted even after controlling for age, gender, obesity, level of education, having work/school the next day, and depressive symptoms, anxiety, and stress.

Nicotine was the substance most strongly associated with sleep disruption and yet another reason to quit smoking.

There was a statistically significant interaction between evening nicotine use and insomnia in relation to sleep duration. Among participants with insomnia, nightly nicotine use was associated with an average 42,47-minute reduction in sleep duration. The effects of nicotine may be particularly significant among individuals with insomnia.

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Source: Florida Atlantic University via